The southern bluefin tuna is a large, streamlined, fast swimming fish with a long, slender caudal peduncle and relatively short dorsal, pectoral and anal fins. The body is completely covered in small scales. The body color is blue-black on the back and silver-white on the flanks and belly, with bright yellow caudal keels in adult specimens. The first dorsal fin colour is grey with a yellow tinge, the second dorsal is red-brown, and the finlets are yellow with a darker border.

Widely distributed throughout the Southern Hemisphere, have complex migration patterns. Fish reaching New Zealand are at least 5 years of age.

The southern bluefin tuna is an opportunistic feeder, preying on a wide variety of fish, crustaceans, cephalopods, salps, and other marine animals.

Spawning fish and larvae are encountered in waters with surface temperatures between 20° and 30°C. Fished for by many countries and is becoming somewhat of a delicacy, especially raw. The flesh is very pink, high in fat and low in moisture, perfect for 'sashimi'.

NZ Marine Fishes: Paul
Collette, B.B. and C.E. Nauen, 1983. FAO Species Catalogue. Vol. 2. Scombrids of the world. An annotated and illustrated catalogue of tunas, mackerels, bonitos and related species known to date. Rome: FAO. FAO Fish. Synop. 125(2):137 p.